- Readily
absorbed from oral mucosa, but rapidly metabolised, hence only has
fleeting durration of action
- Also absorbed from G.I.tract, but due to extensive first pass metabolism,
higher doses ( > 6.5 mg) must be administered
- Absorbed through skin from ointment preparations
- Metabolised by hydrolysis into dinitrates and the mononitrate, which
is the main urinary metabolite

Indications

Prophylaxis
and management of all types of angina pectoris

Sublingual
route

- Rapid onset
and short duration of action, hence useful to relieve acute attacks
- Useful as a single form of treatment if attacks are infrequent
- Effective for immediate prophylaxis if frequency of attacks is predictable,
e.g., may be administered prior to exercise

Buccal
route

- Drug is placed
under the upper lip
- Produces rapid action (in 2-5 minutes) but of short duration
(up to 5 hours)

Skin ointment
/ patches

- Applied on
skin, transdermal absorption
- Absorption may vary depending upon site of application
- Action lasts for about 6 hours

Oral route

- Needs to
be administered in relatively higher doses to overcome hepatic first
pass metabolism
- Suitable for the long term prophylaxis of angina pectoris

- Nitroglycerin
has been the mainstay of angina treatment for years
- Decreases preload and afterload, hence reducing myocardial oxygen
requirement
- Dilates large coronary vessels, redistributing blood to ischaemic
myocardium
- Useful in all types of angina pectoris for prophylaxis or for managing
acute attacks
- May be administered by sublingual, buccal, transdermal or oral route
- Compatible with other drugs, e.g., beta blockers and calcium antagonists